# Copyright 2001, 2002 Dave Abrahams
# Copyright 2003 Vladimir Prus
# Distributed under the Boost Software License, Version 1.0.
# (See accompanying file LICENSE.txt or https://www.bfgroup.xyz/b2/LICENSE.txt)

class set
{
    rule __init__ ( )
    {
    }

    rule add ( elements * )
    {
        for local e in $(elements)
        {
            if ! $($(e))
            {
                $(e) = 1 ;
                self.result += $(e) ;
            }
        }
    }

    rule contains ( element )
    {
        return $($(element)) ;
    }

    rule list ( )
    {
        return $(self.result) ;
    }
}



# Returns the elements of set1 that are not in set2.
#
rule difference ( set1 * : set2 * )
{
    local result = ;
    for local element in $(set1)
    {
        if ! ( $(element) in $(set2) )
        {
            result += $(element) ;
        }
    }
    return $(result) ;
}

NATIVE_RULE set : difference ;


# Removes all the items appearing in both set1 & set2.
#
rule intersection ( set1 * : set2 * )
{
    local result ;
    for local v in $(set1)
    {
        if $(v) in $(set2)
        {
            result += $(v) ;
        }
    }
    return $(result) ;
}


# Returns whether set1 & set2 contain the same elements. Note that this ignores
# any element ordering differences as well as any element duplication.
#
rule equal ( set1 * : set2 * )
{
    if $(set1) in $(set2) && ( $(set2) in $(set1) )
    {
        return true ;
    }
}


rule __test__ ( )
{
    import assert ;

    assert.result 0 1 4 6 8 9 : difference   0 1 2 3 4 5 6 7 8 9 : 2 3 5 7 ;
    assert.result 2 5 7       : intersection 0 1 2   4 5 6 7 8 9 : 2 3 5 7 ;

    assert.true  equal         :         ;
    assert.true  equal 1 1 2 3 : 3 2 2 1 ;
    assert.false equal 2 3     : 3 2 2 1 ;
}
